Addition of an aqueous solution of a lower alcohol to an acid-lubricating oil mixture to obtain a pumpable sludge



United States Patent i ADDITION OF AN AQUEOUS SOLUTION OF A LOWERALCOHOL TO AN ACID-LUBRICAT- ING OIL MIXTURE TO OBTAIN A PUMP- ABLESLUDGE Jere C. Showalter, Baytown, Tex., assignor, by rncsneassignments, to Esso Research and Engineering Company, Elizabeth, N. J.,a corporation of Delaware No Drawing. Application May 8, 1952, SerialNo. 286,819

'10 Claims. or. 196-448 The present invention is directed to the acidtreatment of lubricating oils. More particularly, the invention isdirected to the acid treatment of lubricating oils and the formation ofa pumpable acid sludge. In its more specific aspects, the invention isdirected to a treating operation in which lubricating oil fractions aretreated with sulfuric acid and a pumpable sludge is formed followed byneutralization of the separated acid oil without emulsion difficulties.

The present invention may be described briefly as in volving a processfor separating a pumpable acid sludge from an acid treated lubricatingoil fraction in admixture with said sludge, the particular feature ofthe invention being the addition to the admixture of the lubricating oilfraction and acid sludge of a small but effective amount of an aqueoussolution of a water soluble aliphatic alcohol having from 1 to 4 carbonatoms in the molecule. The admixture containing alcohol is then settledand a pumpable acid sludge is separated from the treated lubricating oilfraction.

My invention also contemplates acid treatment of the lubricating oilfraction in combination with the subsequent addition of an aqueoussolution of a water soluble aliphatic alcohol to form a pumpable sludgewhich is separated. I also contemplate the subsequent neutralization ofthe separated acid oil with a treating agent which does not form anemulsion with the acid treated lubricating oil fraction. In short, byaddition of a water soluble aliphatic alcohol to the admixture of oiland sludge prior to settling and separating same and the neutralizationof, the separated acid oil allows such a process to be employed in acontinuous operation whereas heretofore without the ready settling andseparation and the neutralization of the acid oil without formation ofemulsions, it was necessary to provide extensive settling and separatingtimes which required batch operations.

The lubricating oil fraction treated in accordance with the presentinvention may be any lubricating oil fraction, such as refined in modernpetroleum refineries. It may be a lubricating oil fraction from aCoastal or Mid- Continent crude or it may be a lubricating oil fractionfrom a Pennsylvania type crude. It should suflice to say that myinvention involves the acid treatment of any lubricating oil fractionwhich is normally subjected to such acid treatment.

The sulfuric acid employed in the practice of the present invention maybe the commercial black acid usually available in petroleum refinery. Itmay be an alkylation spent sulfuric acid such as discarded from sulfuricacid alkylation operations. The sulfuric acid may be a concentratedsulfuric acid or any of the usual commercial acids having a Baum gravityof about 66 which is usually used in lubricating oil treatingoperations.

The amount of acid employed may range from about 5 pounds of acid perbarrel up to about 50 pounds of acid per barrel and an amount in therange from about pounds of acid per barrel of oil up to about 35 poundsof acid perbarrel of oil will be preferred for most stocks.

The alcohols mentioned before may be used in an.

amount in the range between 0.1% and 1.0% by volumeas an aqueoussolution containing from about 10% to about 50% by volume of alcohol.For example, an aque-- ous solution of isopropyl alcohol in an amount inthe range between 0.5% and 0.75% based on the, acid oil of a 10% to 50%aqueous solution gives very satisfactory results.

The treating reagent employed to neutralize the sul furic acid treatedoil will ordinarily comprise an aqueous solution of an alkali metal saltof preferably water-soluble sulfonic acids, such as a sodium salt ofsulfonic acids, an alkali metal hydroxide, such as sodium hydroxide, andan alkali metal salt of an inorganic acid, such as sodium chloride orsodium sulfate.

The water-soluble sulfonic acid from which the alkali metal saltsemployed in the treating reagent are produced may be either an aromaticsulfonic acid or an alkyl sulfonic acid. For example, the sodium saltmay be produced by neutralizing aromatic sulfonic acids resulting fromthe treatment of benzene, toluene and xylene with strong sulfuric acid.The treating reagent suitably may be prepared by neutralizing the acidtreated oil produced in the formation of aromatic solvents. The aromaticsulfonic acids from which the salts are produced for use in the treatingreagent may be obtained from acid solutions resulting from acidtreatment of low molecular Weight lubricating oils, such as solvent oilshaving a viscosity of about SSU at F.

It is also possible to employ alkyl sulfonic acids in the preparation ofthe alkali metal salts of sulfonic acid for use in the treating reagent.For example, heptyl sulfonic acid neutralized with sodium hydroxide maybe used. The other alkyl sulfonic acids, such as the other members ofthe series of paraffiuic hydrocarbons, such as hexane, octane, nonane,decane, undecane, dodecane and the like may be employed as startingmaterials for producing alkyl sulfonic acids. The neutralization agentmay conveniently have a composition as follows:

Table Percent Alkali metal hydroxide 0.5 5 Alkali metal salt of sulfonicacid 10 -15 Alkali metal salt of inorganic acid 5 7.5 Water 72.5-84.5

The solution of the treating reagent should have a specific gravity noless than 1.10. Solutions of the treating reagent prior to dilution withwater may range from 1.2 to 1.3 in specific gravity.

The treating reagent employed in the process of the present inventionshould contain the several components recited before. It is necessary tohave the inorganic salt present to confer gravity differential betweenthe oil being treated and the treating reagent to facilitate settlingand prevent emulsions. The alkali metal salt of sulfonic acid isbelieved to act as a solutizer for the alkali metal salts of organic andinorganic acids which result from neutralization of such acidity withthe free alkali metal hydroxide in the treating reagent. On omission ofthe alkali metal salts of sulfonic acid, the salts resulting fromneutralization may remain in the oil and contribute to unsatisfactoryresults in that they may serve as nuclei for water and contribute toemulsion formation.

The alkali metal hydroxide in small amounts allows neutralization oforganic and inorganic acidity and in the presence of the alkali metalsalts of sulfonic acid and an inorganic acid is effective inneutralizing substantially larger quantities of organic and inorganicacidity than is possible conventionally.

When neutralizing acid oils resulting from treating such lubricating oilfractions as mentioned before, it will be desirable to use an amount ofthe treating reagent in the range from about 3% by volume based on theacid oil up to about by volume. Satisfactory results may be obtainedemploying about 3% by volume to about 6% by volume of the treatingreagent described before.

The acid treatment of the lubricating oil fraction may be conducted inany type of suitable contacting equipment available in the modernpetroleum refineries. The contacting operation may be done batch-wisebut preferably a continuous operation followed by addition of an aqueoussolution of a water soluble alcohol to the admixture of acid sludge andoil resulting from the treating operation is employed. Thealcohol-containing admixture is then settled in the usual type ofsettling equipment and a separation made between the acid oil and theacid sludge after addition of the aqueous solution of water solublealcohol. By virtue of adding the aqueous solution of water solublealcohol to the admixture, it is possible to obtain a pumpable acidsludge and also to make a cleaner separation than was possibleheretofore. As a result of such improved operations the yields of acidtreated oil have been improved.

Similarly, the neutralization treatment with the treating reagent supramay be conducted in suitable contacting equipment and preferably on acontinuous basis. The acid oil after separation from the acid sludge isadmixed in the amounts given with the treating reagent to allow intimatecontact of the treating reagent and neutralization of inorganic andorganic acidity of the lubricating oil. As a result of such a contactthe inorganic and organic acidities are neutralized and an oil ofimproved quality is obtained after suitable wash, for example, with hotwater followed by settling to remove the wash water and drying asdesired. My sequence of operations allows the process to be carried outwithout the attendant difficulties normally encountered in the priorart. Thus the employment of the aqueous solution of the aliphaticalcohol gives a clean and sharp separation of a pumpable acid sludge andthe neutralization with the treating reagent eliminates the formation ofemulsions which has plagued refiners of lubricating oil for over years.

The invention will be further illustrated by the following runs where,in one instance, a Coastal lubricating oil distillate was acid treatedand after a sulficient settling time for complete reaction of thesulfuric acid with the lubricating oil distillate to form an admixtureof acid oil and sludge, 0.3% by volume of 91% isopropyl alcohol wasadded to the admixture in 0.1% by volume increments. Thereafter 0.3% byvolume of water was added in 0.1% by volume increments and the sludgecoagulated and removed. The separated sludge was fluid and soft intexture.

A Coastal lubricating oil distillate was treated with sulfuric acid andthe resulting admixture of acid oil and sludge was separated into twoportions. The first portion had added to it 0.5% by volume of water. Thesecond portion had added to it 0.5% of a 20% by volume aqueous solutionof isopropyl alcohol. In both cases, the sludge coagulateed but thesludge separated from the portion to which water only was added was hardand mealy while the sludge recovered when alcohol was added was soft andfluid.

In a still further run, :1 Coastal lubricating oil distillate wastreated with sulfuric acid and divided into two portions. In the firstinstance 0.7% of water was added to coagulate the sludge. To the secondportion 0.7% of a 20% by volume isopropyl alcohol solution was added.

In the first case where water only was employed the sludge withdrawn washard and mealy. Where the aqueous alcohol solution was used, the sludgewithdrawn was soft and fluid. 1n addition to this improved result theyield of acid oil obtained in the second instance was 5.5% by volumegreater than that in the first instance where water only was used toseparate the acid sludge.

The acid oil such as obtained from the last operation described whereaqueous alcohol was used may then be neutralized with 3% to 6% by volumeof the treating reagent described above.

In a continuous operation a lubricating oil distillate may be contactedwith suitable amounts of sulfuric acid, such as commercial sulfuric acidof 98% H2504 at a temperature from to P. which temperature results fromheating the lubricating oil prior to acid treatment to remove any waterwhich may be present therein. After the acid and the lubricating oil hasbeen contacted for a sufiicient time for reaction to form a sludge, theadmixture of acid sludge and acid oil then has admixed with it anaqueous solution of isopropyl alcohol such as one containing about 20%aicohol in a range from 0.5% to 0.75% by volume based on the acidtreated oil. The acid sludge separates cleanly from the acid oil and maybe withdrawn as a pumpable sludge while the acid oil is then admixedwith about 3% to 6% by volume of the treating reagent described beforeand then allowed, after contacting a suflicient length of time, tosettle with the treating reagent being withdrawn. The so-neutralized oilis then washed with hot water and the wash water removed. Following thewash with water the oil may be dried by heating and subjected to reducedpressure to flash off water vapor, if desired.

The nature and objects of the present invention having been completelydescribed and illustrated, what I wish to claim as new and useful and tosecure by Letters Pat out is:

1. A process for separating a pumpable acid sludge from an acid treatedlubricating oil fraction in admixture with said sludge which comprisesadding to said mixture an amount in the range between 0.5% and 0.75% byvolume of an aqueous solution containing from about 10% to about 50% byvolume of a water soluble aliphatic alcohol having from 1 to 1 carbonatoms in the molecule, settling the alcohol-containing admixture andseparating a pumpable acid sludge from the treated lubricating oilfraction.

2. A process in accordance with claim 1 in which the alcohol is methylalcohol.

3. A process in accordance with claim 1 in which the alcohol is ethylalcohol.

4. A process in accordance with claim 1 in which the alcohol is a propylalcohol.

5. A process in accordance with claim 1 in which the alcohol is a butylalcohol.

6. A process in accordance with claim 1 in which the alcohol isisopropyl alcohol.

7. A method for treating a lubricating oil fraction which comprisescontacting a lubricating oil fraction with sulfuric acid at atemperature in the range from 160 to 180 F. to form an admixture oflubricating oil and an acid sludge, adding to said admixture an amountin the range between 0.5% to 0.75% by volume of an aqueous solutioncontaining from about 10% to about 50% by volume of a water solublealiphatic alcohol having from 1 to 4 carbon atoms in the molecule,settling the alcoholcontaining admixture and separating a pumpable acidsludge from the treated lubricating oil fraction.

8. A process in accordance with claim 7 in which the alcohol isisopropyl alcohol.

9. A continuous process for treating a lubricating oil fraction whichcomprises contacting a lubricating oil fraction with sulfuric acid at atemperature in the range from 160 to 180 F. to form an admixture of saidlubricating oil fraction and an acid sludge, adding to said admixture anamount in the range between 0.5% and 0.75% 1,233,700 Petrolf July 17 1917 by volume of an aqueous solution containing from about 1,418,368Ellis June 6, 1922 1.0% to about 50% by volume of a Water solublealiphatic 1,938,322 De Groote et a1. Dec. 5, 1933 alcohol having from 1to 4 carbon atoms in the molecule, 2,293,253 Galindo et a1. Aug. 18,1942 settlin the alcohol-containing admixture, separating and 52,418,784 McCormick et a1. Apr. 8, 1947 separately recovering a pumpableacid sludge and the 2,487,103 Cone et al. Nov. 8, 1949 treatedlubricating oil fraction, and neutralizing the treat- 2,581,064Archibald Ian, 1, 1952 ed lubricating oil fraction with a treatingreagent in an 2,685,558 Hodges Aug. 3, 1954 amount in the range fromabout 3% to 6% by volume OTHER REFERENCES comprising an aqueous solutionof an alkall metal hy- 0 droxide, an alkali metal salt of an inorganicacid and an Rlchter: Orgamc Chmmstry: VOL Nordeman Publish alkali metalSalt of a sulfonic acid. ing (30., Inc., 215 4th Ave., New York, N. Y.,pages 167-8 10. A process in accordance with claim 9 in which (1944)-the alcohol is isopropyl alcohol.

References Cited in the file of this patent UNITED STATES PATENTS i1,196,274 Petrofi Aug. 29, 1916

1. A PROCESS FOR SEPARATING A PUMPABLE ACID SLUDGE FROM AN ACID TREATEDLUBRICATING OIL FRACTION IN ADMIXTURE WITH SAID SLUDGE WHICH COMPRISESADDING TO SAID MIXTURE AN AMOUNT IN THE RANGE BETWEEN 0.5% AND 0.75% BYVOLUME OF AN AQUEOUS SOLUTION CONTAINING FROM ABOUT 10% TO ABOUT 50% BYVOLUME OF A WATER SOLUBLE ALIPHATIC ALCOHOL HAVING FROM 1 TO 4 CARBONATOMS IN THE MOLECULE, SETTLING THE ALCOHOL-CONTAINING ADMIXTURE ANDSEPARATING A PUMPABLE ACID SLUDGE FROM THE TREATED LUBRICATING OILFRACTION.